This invention relates to a system to measure and monitor selected operating parameters of a solenoid operated valve. It relates particularly to a valve diagnostic system that is able to test, measure and analyze a number of selected operating parameters associated with solenoid operated valves to determine whether or not the valve is operating within its design parameters and to record over time any changes in the selected parameters that could affect the continuous and reliable operation of the valve. The invention is especially useful in the field of valve diagnostics.
Industrial valves are widely used for a number of different applications in the power industry and many other industries. Industrial valves are usually operated by electromagnetic solenoids or electric motors or compressed air to open, closed and intermediate positions in order to control the flow of fluids, such as cooling water, that pass through the valve. Continuous and reliable operation of the valve is essential.
The valve user industries and the valve manufacturing industry have had a need to develop apparatus, methods and systems to measure, test and monitor various operating parameters associated with valves and to detect any significant changes in any of these valve operating parameters being measured, tested and monitored, that could affect the continuous and reliable operation of the valve.
U.S. Pat. No. 4,542,649 to Charbonneau et al. discloses a recently developed valve testing and monitoring system for an electric motor operated valve that measures, records and correlates a number of valve operating parameters, such as valve stem load, valve stem movements, valve stem torque, spring pack movement and motor current. The information provided by the system described in the Charbonneau et al. patent provides a direct indication to the operator or test engineer of any valve problems, such as excessive or inadequate packing loads, excessive inertia, incorrectly set limit and torque switches, malfunctioning thermal overload devices, excessive stem thrust loads, gear train wear and damage to the valve stem.
As a result of the teachings of the Charbonneau et al. patent, efforts have been made by Movats, Inc., the assignee of the Charbonneau et al. patent, and the assignee of the present patent application, to develop additional apparatus and valve diagnostic systems by which the operation and performance of different types of valves could be easily measured, tested, monitored and analyzed. U.S. Pat. Nos. 4,690,003; 4,693,113; 4,787,245; 4,831,873; 4,488,996; 4,912,984; 4,930,228; 5,000,040 and 5,142,906 describe a number of the valve monitoring and diagnostic systems developed by Movats, Inc. for electric motor operated valves. U.S. Pat. Nos. 4,805,451; 4,856,327; 4,976,144; 5,109,692 and 5,197,328 describe several of the valve monitoring and diagnostic systems developed by others for electric motor operated and compressed air operated valves. However, there has been very few valve monitoring and diagnostic systems developed for solenoid operated valves.
In the past, solenoid operated valves were tested by maintenance personnel using hand-held electrical meters to measure the electrical solenoid coil current and control signals and a vernier ruler or scale to measure the axial position of the valve stem during the operation of the valve. These measurements were often difficult to make and crude and left the potential for significant error. Furthermore, these measurements and practices frequently did not detect electrical or mechanical degradations in the valve components or provide an overall diagnosis of the condition of the valve.